This invention relates to an improved means for effecting the opening of pockets formed in a continuous strip of folded or U-shaped stock material provided with spaced-apart vertical heat seals.
Apparatus for the manufacture of sealed packages from strip stock are well-known in the art as illustrated by U.S. Pat. Nos. 3,453,799, 3,478,492 and 3,563,001 to Cloud et al. all of which are herein incorporated by reference. This type of equipment is suitable for the continuous production of a series of filled packages from a continuous length of heat-sealable flexible material; preferably a plastic coated paper or foil.
In operation, a continuous length of strip stock is drawn through a guide or strip plow where it is folded into a generally U-shaped configuration, the fold being disposed at the bottom and the strip edges disposed at the top. The folded strip is then passed through a sealing station where longitudinally-spaced, vertically-extending heat seals are made across the entire height of the strip. In this manner pockets are formed, each pocket being disposed between a pair of vertically-extending heat seals which adhere the pocket sidewalls. After the strip has been sealed in the manner described, it is moved to a filling station where a granular material, in the desired amount, is inserted into each pocket.
Typically the filling station, as shown in the aforementioned patents, consists of a rotating turret provided with a plurality of collapsible suction heads disposed at circumferentially spaced intervals about the perimeter of the wheel, an overhead rotation filling drum equipped with a plurality of discharge tubes or funnels and an overhead air nozzle. In operation the continuous strip of pockets is fed to the rotating turret at a rate whereby each pocket engages a separate suction head and is positioned directly beneath a separate discharge tube. Vacuum is applied to the collapsible suction head to cause a collapse or retraction of the head thereby pulling the inwardly-facing sidewall of the pocket back and away from the outwardly-facing sidewall. In this manner the pocket should be opened to permit filling. It has been found, however, that when employing light-weight films as the stock material, it is necessary to provide additional means to assist in opening the pockets prior to filling. The three aforementiond patents each disclose the use of an overhead nozzle for providing a continuous stream of air to spread the top edges of the sidewalls. The filling tube may then be lowered down into the opened pocket to discharge the desired amount of granular material and then withdrawn.
After filling, the strip of filled pockets is delivered from the rotating wheel of the filling station to cutoff and sealing stations. The individual sealed pockets or pouches may then be stacked and packaged as desired.